We travelled on an older plane and paid approximately $1500 return.
Business class is basically similar to Australian domestic business class, with more leg room and more comfortable seats than economy.
The staff were very friendly responsive and should be congratulated on their performance. The food was fine, as long as you do not expect the same quality or variety you get in long haul business class.
We sat in row 6 which was good, as they often put families in row 1. Also the overhead TV screens were on all night, and their glow would have made sleeping in the front rows much harder.
There are no TV screens in the seats, so preloaded iPads are available at no cost. However the selection of movies and shows is very thin. As a result, if you have your own tablet, then I would suggest that you download what you want to watch before hand - otherwise it can be a long flight !
In summary, we would be happy to fly with jet star business again.